Roman Abramovich, the billionaire owner of Chelsea FC, has splashed out £70 million for a stake in a British telecoms company.

The investment values Truphone, a London-based group that specialises in international phone services for corporate customers, at £300 million.

Mr Abramovich, through his investment vehicle Minden, will own a 23.3 per cent stake in Truphone.

The backing is a huge coup for privately owned Truphone, which has struggled in recent years to live up to its promise. It supplies business customers with a SIM card that works as a local number when the mobile phone is used overseas and